/Engine/Plugins/Runtime/WaveTable/Source/WaveTable/Public/WaveTableSampler.h
If set to one-shot, returns the first index where a reverse or stall occurred in the provided interpolated index, ignoring samples where a "sync" request took place. If set to looping, always INDEX_NONE as looping does not support a "finished" state.
int32 GetIndexFinished() const